The present invention is directed to hot melt or phase change inks. More specifically, the present invention is directed to cyan phase change inks suitable for use in phase change ink jet printers. One embodiment of the present invention is directed to a phase change ink composition comprising (a) a phase change carrier, (b) a cyan colored resin or wax comprising the reaction product of (i) a cyan colorant having at least one functional group selected from (A) hydroxyl groups, (B) primary or secondary amino groups, (C) mercapto groups, or (D) mixtures thereof, and (ii) an isocyanate, and (c) an organic acid selected from (i) organic sulfonic acids, (ii) organic phosphinic acids, (iii) organic phosphonic acids, or (iv) mixtures thereof.
In general, phase change inks (sometimes referred to as xe2x80x9chot melt inksxe2x80x9d) are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the recording substrate, they quickly solidify to form a predetermined pattern of solidified ink drops. Phase change inks have also been used in other printing technologies, such as gravure printing, as disclosed in, for example, U.S. Pat. No. 5,496,879 and German Patent Publications DE 4205636AL and DE 4205713AL, the disclosures of each of which are totally incorporated herein by reference.
Phase change inks for color printing typically comprise a phase change ink carrier composition which is combined with a phase change ink compatible colorant. In a specific embodiment, a series of colored phase change inks can be formed by combining the ink carrier composition with compatible subtractive primary colorants. The subtractive primary colored phase change inks can comprise four component dyes, namely, cyan, magenta, yellow and black, although the inks are not limited to these four colors. These subtractive primary colored inks can be formed by using a single dye or a mixture of dyes. For example, magenta can be obtained by using a mixture of Solvent Red Dyes or a composite black can be obtained by mixing several dyes. U.S. Pat. Nos. 4,889,560, 4,889,761, and 5,372,852, the disclosures of each of which are totally incorporated herein by reference, teach that the subtractive primary colorants employed can comprise dyes from the classes of Color Index (C.I.) Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, and Basic Dyes. The colorants can also include pigments, as disclosed in, for example, U.S. Pat. No. 5,221,335, the disclosure of which is totally incorporated herein by reference. U.S. Pat. No. 5,621,022, the disclosure of which is totally incorporated herein by reference, discloses the use of a specific class of polymeric dyes in phase change ink compositions.
Phase change inks have also been used for applications such as postal marking and industrial marking and labelling.
Phase change inks are desirable for ink jet printers because they remain in a solid phase at room temperature during shipping, long term storage, and the like. In addition, the problems associated with nozzle clogging as a result of ink evaporation with liquid ink jet inks are largely eliminated, thereby improving the reliability of the ink jet printing. Further, in phase change ink jet printers wherein the ink droplets are applied directly onto the final recording substrate (for example, paper, transparency material, or the like), the droplets solidify immediately upon contact with the substrate, so that migration of ink along the printing medium is prevented and dot quality is improved.
Compositions suitable for use as phase change ink compositions are known. Some representative examples of references disclosing such materials include U.S. Pat. Nos. 3,653,932, 4,390,369, 4,484,948, 4,684,956, 4,851,045, 4,889,560, 5,006,170, 5,151,120, 5,372,852, 5,496,879, European Patent Publication 0187352, European Patent Publication 0206286, German Patent Publication DE 4205636AL, German Patent Publication DE 4205713AL, and PCT Patent Application WO 94/04619, the disclosures of each of which are totally incorporated herein by reference. Suitable materials can include paraffins, microcrystalline waxes, polyethylene waxes, ester waxes, fatty acids and other waxy materials, fatty amide containing materials, sulfonamide materials, resinous materials made from different natural sources (tall oil rosins and rosin esters, for example), and many synthetic resins, oligomers, polymers, and copolymers.
U.S. Pat. No. 5,780,528 (Titterington et al.), the disclosure of which is totally incorporated herein by reference, discloses isocyanate-derived colored resins made by reacting an alcohol and/or amine, an isocyanate, and a nucleophilic molecule containing a chromogen. The isocyanate-derived colored resins are useful as colorant materials in phase change ink compositions.
U.S. Pat. No. 5,919,839 (Titterington et al.), the disclosure of which is totally incorporated herein by reference, discloses colored waxes made by reacting selected nucleophiles, including alcohol containing colorants, with an isocyanate. A phase change ink is made by blending the colored wax with a clear ink carrier composition. The clear ink carrier composition can be a fatty amide-based material and/or a combination of isocyanate-derived resins in which the order of addition of the isocyanate and the different nucleophiles can tailor the distribution of di-urethane, mixed urethane/urea, and/or di-urea molecules in the final resin product. The colored wax materials are useful as ingredients with phase change ink carrier compositions to make phase change ink jet inks.
U.S. Pat. No. 6,015,847 (Titterington et al.), the disclosure of which is totally incorporated herein by reference, discloses a phase change ink composition comprising a phase change carrier composition, at least one compatible phase change magenta colorant material, and at least one organic sulfonic acid compound. The sulfonic acid stabilizes the magenta dye.
While known compositions and processes are suitable for their intended purposes, a need remains for improved phase change inks. In addition, a need remains for improved cyan phase change inks. Further, a need remains for cyan phase change inks with improved thermal stability. Additionally, a need remains for cyan phase change inks with reduced image defects. There is also a need for cyan phase change inks that do not become discolored or lose color over time in a phase change ink jet printer. In addition, there is a need for cyan phase change inks containing colorants of high purity. Further, there is a need for cyan phase change inks with excellent spectral strengths. Additionally, there is a need for cyan phase change inks with substantially transparent colorants. A need also remains for cyan phase change inks with desirable electrical conductivity values. In addition, a need remains for cyan phase change inks that exhibit good fold durability on printed media.
The present invention is directed to a phase change ink composition comprising (a) a phase change carrier, (b) a cyan colored resin or wax comprising the reaction product of (i) a cyan colorant having at least one functional group selected from (A) hydroxyl groups, (B) primary or secondary amino groups, (C) mercapto groups, or (D) mixtures thereof, and (ii) an isocyanate, and (c) an organic acid selected from (i) organic sulfonic acids, (ii) organic phosphinic acids, (iii) organic phosphonic acids, or (iv) mixtures thereof.